s .  ** 


x*J  T>-  ^f  JSf  *i^EB 

fe 

' .     .-          W  ,,        ^k.     __.<S\      •   .-   ^\    r-, 


ii^Ji 


SEFtM 

MJilT  r-^xL      ^y/^    ,vCMv 


.«,  i 


UNIVERSITY  LIBRARY 

(^  UNIVERSITY  OF  ILLINOIS  AT  URBANA-CHAMPAIGN 

4^£. .  The  person  charging  this  material  is  responsible  for  its 

renewal  or  return  to  the  library  on  or  before  the  due      $jj(!%!w&k 

date.  The  minimum  fee  for  a  lost  item  is  $125.00,       *fV^ 

$300.00  for  bound  journals. 

Theft,  mutilation,  and  underlining  of  books  are  reasons 

for  disciplinary  action  and  may  result  in  dismissal  from 

the  University.  Please  note:  self-stick  notes  may  result 

in  torn  pages  and  lift  some  inks. 

Renew  via  the  Telephone  Center  at  217-333-8400, 

846-262-1510  (toll-free)  orcirclib@uiuc.edu. 

Renew  online  by  choosing  the  My  Account  option  at: 

http://www.library.uiuc.edu/catalog/ 


^*VuT^  \*^< 

45  SP  m 
i 

~s 


J 


UNIVERSITY  OF  ILLINOIS 


Agricultural  Experiment  Station 


BULLETIN  No.   102 


THE    CONSTRUCTION    OF    SILOS 


BY  WILBER  J.  ERASER 


URBANA,  ILLINOIS,  JUNE,  1905 


SUMMARY  OF  BULLETIN  No.  102 


INTRODUCTION. — The  object  of  this  bulletin  is  to  direct  atten- 
tion to  some  important  points  in  building  silos,  both  in  material  used 
and  in  manner  of  construction.  Page  i 

ESSENTIALS  OF  A  SILO. — To  preserve  the  silage  perfectly  the 
silo  wall  must  be  rigid  and  air-tight.  Page  T 

LOCATION. — That  the  labor  of  feeding  may  be  reduced  to  the 
minimum,  the  silo  should  be  placed  as  near  the  manger  as  possible. 

Page  3 

FORM  OF  SILO. — It  is  practically  impossible  to  construct  a 
square  wood  silo  with  rigid  walls,  and  as  silage  usually  spoils  more 
or  less  in  the  corners,  it  is  perfectly  clear  that  the  round  silo  is  the 
only  proper  form.  Page  7 

PROPORTION  AND  CAPACITY. — The  deeper  the  silo  the  greater 
the  pressure  and  the  more  compactly  will  the  silage  be  pressed  to- 
gether. To  be  well  proportioned,  the  height  should  not  be  more 
than  twice  the  diameter.  Table  i  gives  the  capacity  of  silos. 

Page     7 

Round  Wood  Silo  Plastered  with  Cement  Page  1 1 

Foundation  Page  n 

Sill  and  studs  Page   13 

Lath  and  plaster  Page   18 

Ventilation  Page  20 

Sheeting  Page  22 

Itemized  cost  Page  24 

Concrete  Silos  Page  32 

Brick  Silos  Page  35 

Stone  Silos  Page  36 

Stave  Silos  Page  37 


THE   CONSTRUCTION  OF  SILOS 

BY  WTLBER  J.  FRASER,  CHIEF  IN  DAIRY  HUSBANDRY 

INTRODUCTION 

There  has  been  much  discussion  through  the  agricultural  press 
and  at  farmers'  institutes  concerning  the  importance  of  the  silo  and 
the  advantages  and  disadvantages  of  the  different  styles  of  con- 
struction. As  yet,  however,  comparatively  few  dairymen  and  stock 
raisers  of  Illinois  fully  appreciate  the  value  of  silage,  and  as  there 
are  not  one-tenth  as  many  silos  in  the  state  as  the  economy  of  silage 
as  a  feed,  especially  for  dairy  cows,  would  warrant,  the  Experiment 
Station  has  deemed  it  wise  to  issue  two  bulletins  on  this  subject. 

Bulletin  No.  101,  recently  published,  discusses  the  subject  of 
crops  for  the  silo  and  cost  of  filling.  The  aim  of  this  bulletin  is  to 
direct  attention  to  some  of  the  essential  points  in  silo  construction 
and  also  to  show  the  serious  defects  in  some  styles  of  silos,  both  in 
the  material  used  and  in  the  manner  of  construction.  Cheap  silos 
which  are  poorly  built  have  done  much  to  injure  the  cause  of  silage, 
for  since  they  do  not  preserve  their  contents  perfectly  there  is  nec- 
essarily great  loss.  The  problem  is,  therefore,  to  build  an  enduring, 
air-tight,  rigid  structure  at  least  expense. 

ESSENTIALS  OF  A  SILO 

There  are  several  points  that  must  be  closely  observed  in  making 
silage  if  it  is  to  be  well  preserved,  and  the  neglect  of  any  one  of 
these  will  make,  in  the  final  result,  the  difference  between  success  and 
failure.  These  essentials  are  close  packing,  when  the  crop  is  at 
the  proper  stage  of  maturity,  in  an  air-tight  structure  having  per- 
fectly rigid  walls. 

The  stage  of  maturity  and  method  of  packing  were  treated  in 
Bulletin  No.  101  (a  copy  of  which  can  be  obtained  from  the  Illinois 
Experiment  Station,  Urbana,  Illinois.)  Of  equal  if  not  greater 
importance,  is  the  proper  construction  of  the  silo.  If  the  sides  of 
the  silo  are  not  air-tight,  the  air  which  passes  through  will  cause  the 
silage  to  spoil,  and  if  the  walls  are  not  perfectly  rigid,  the  pressure 
of  the  silage  will  cause  them  to  spring  out,  allowing  the  air  to 
enter  between  the  silage  and  the  wall.  In  either  case  the  result 
will  be  the  same — decayed  silage. 

I 


BULLETIN  No.  102. 


\June, 


CUT  1.— LARGE  CEMENT  SILO  TO  WHICH  Cow  STABLE  is  TO  BE  EXTENDED. 

The  outward  pressure  on  the  wall  of  a  silo  filled  with  cut  corn 
is  about  ii  pounds  for  every  foot  in  depth;  making  a  pressure 
of  no  pounds  at  a  depth  of  10  feet;  330  pounds  at  a  depth  of  30 
feet;  and  the  enormous  pressure  of  440  pounds  per  square  foot  at 
a  depth  of  forty  feet.  This  increase  in  pressure  as  the  depth  in- 
creases must  be  considered  in  silo  construction  and  the  lower  portion 
made  much  the  stronger. 

Before  building  a  silo  the  most  careful  attention  should  be  given 
to  location,  size,  form,  and  method  of  construction.  These  will 
differ  somewhat  according  to  locality  and  individual  needs.  A  brief 
discussion  of  these  questions  follows : 


CUT  2. — Two  ROUND  SILOS  FORMING  END  OF  BARN. 


1905.] 


THE  CONSTRUCTION  OF  SILOS. 


CUT  3. — SILO  LOCATED  AT  INTERSECTION  OP  Cow  STABLES. 
LOCATION 

As  silage  contains  about  80  percent  water  it  is  a  heavy  feed  to 
handle  and,  to  avoid  unnecessary  labor  in  feeding,  the  silo  should 
be  placed  as  near  the  manger  as  possible,  preferably  at  one  end  of  the 
feeding  alley.  If  the  silo  is  inside  the  barn  the  silage  chute  should 
be  provided  with  a  door  which  should  be  kept  closed  to  prevent  the 
silage  odors  from  entering  the  barn  at  milking  time,  thus 'avoiding 
the  possibility  of  their  being  absorbed  by  the  milk. 


CUT  4  —OCTAGONAL  SILO  LOCATED  IN  CORNER  OP  BARN. 


BULLETIN  No.  102. 


\June, 


CUT  5.— SHOWING  CONNECTION  OF  SILO  WITH  BARN. 


CUT  6. — SILAGE  CART  FOR  USE  ON  CEMENT  FLOOR. 


1905.'] 


THE  CONSTRUCTION  OF  SILOS. 


CUT  7. — WHERE  NECESSARY  TO  FILL  HAY  LOFT  FROM  END  OF  BARN 

AT  WHICH  SILO  is  LOCATED,  A  MOVABLE  TRACK  AND  CAR 

MAY  BE  USED  TO  CARRY  SILAGE  TO  MANGER. 


CUT  8.— SILAGE  CAR  TO  RUN  ON  MOVABLE  TRACK. 


G 


BULLETIN  No.  102. 


[June, 


Where  there  is  a  smooth  level  floor  from  the  silo  through  the 
feeding  alley,  a  cart  similar  to  the  one  shown  in  Cut  6  will  prove 
a  great  convenience  in  feeding.  When  built  outside  the  barn  the  silo 
should  be  within  a  few  feet  of  it  and  connected  by  a  covered  pass- 
age. Where  it  is  desired  to  drive  up  to  the  barn  with  grain  only, 
the  arrangement  may  be  as  in  Cut  5.  If  it  is  necessary  to  fill  the 
hay  loft  from  the  end  of  the  barn  at  which  the  silo  is  located,  a 
movable  track  for  the  silage  car  can  be  arranged  to  extend  from  the 
silo  to  the  barn,  (Cut  7)  with  a  car  constructed  as  shown  in  Cut  8. 
Cuts  I,  2,  3,  and  4  show  how  silos  may  be  conveniently  located. 


CUT  9. — CHEAP  OCTAGONAL  SILO  WHICH  DID  NOT  PRESERVE  ITS 
CONTENTS  PERFECTLY.    THIS  IN  NOT  A  GOOD  SHAPE 
EVEN  WHEN  PROPERLY  CONSTRUCTED. 


1905,']  THE  CONSTRUCTION  OF  SILOS.   •  7 

FORM  OF  SILO 

Nearly  every  one  who  builds  a  silo  adds  some  new  feature,  giving 
rise  to  a  great  variety  of  shapes  and  methods  of  construction.  Be- 
fore building  a  silo  it  is  well  to  consider  both  the  advantages  and  the 
disadvantages  of  the  different  styles,  as  well  as  the  cost  of  each. 
It  should  be  borne  in  mind,  however,  that  no  silo  is  cheap,  no  matter 
how  small  the  first  cost,  if  it  does  not  preserve  the  silage  perfectly. 
The  first  silos  in  this  country  were  usually  built  inside  the  barn  and 
consequently  the  square  form  was  commonly  used  in  order  to 
utilize  the  space  more  completely.  The  square  silo  has  not  proved 
satisfactory,  however,  as  it  is  practically  impossible  to  build  this 
form  so  that  the  side  walls  will  not  spring  out  and  allow  the  air  to 
pass  down  between  the  silage  and  the  wall,  which  invariably  results 
in  the  rotting  of  the  silage.  Another  difficulty  with  the  square 
form  is  that  the  silage  does  not  settle  readily  in  the  corners  and 
there  is  consequently  considerable  loss  from  this  cause.  Square  silos 
having  heavy  cement  walls  are  shown  in  Cut  10,  but  even  these 
have  cracked,  allowing  the  air  to  enter. 

An  example  of  great  loss  owing  to  the  form  and  faulty  con- 
struction came  under  the  writer's  notice  a  few  years  ago  when  a 
square  silo  with  a  capacity  of  fifty  tons,  was  built  with  air-tight, 
but  not  rigid  walls.  Simply  the  springing  of  the  sides  of  the  silo 
allowed  the  air  to  gain  access  to  the  silage  to  such  an  extent  that  the 
entire  fifty  tons  spoiled  completely.  Since  for  mechanical  reasons 
it  is  practically  impossible  to  build  a  square  wood  silo  with  perfectly 
rigid  walls,  the  round  silo  is  the  only  proper  form. 

Silage  has  been  put  up  at  the  University  for  the  past  seventeen 
years.  The  first  silos  were  square  and  built  inside  the  barn.  These 
were  made  of  two  thicknesses  of  %  inch  flooring  with  paper  between. 
After  having  been  used  seven  or  eight  years  the  double  walls 
began  to  show  signs  of  decay,  and  after  nine  years  the  walls  were  so 
badly  rotted  that  the  silo  was  useless.  If  silos  are  to  be  built  of 
wood  the  wall  should  be  of  but  one  thickness.  The  difficulty  with 
double  walls  is  that  moisture  gets  in  between  the  two  layers  of  wood 
and  as  it  does  not  dry  out  readily,  decay  follows  rapidly. 

PROPORTION  AND  CAPACITY  OF  SILOS 

To  obtain  satisfactory  results,  silage  must  be  in  perfect  condi- 
tion when  fed.  Since  fermentation  soon  takes  place  when  silage 
is  exposed  to  the  air,  the  silo  should  not  be  of  too  great  diameter. 


BULLETIN  No.  102. 


[June, 


1905.}  THE  CONSTRUCTION  OF  SILOS.  9 

Not  more  than  eight  square  feet  of  surface  should  be  allowed  for 
each  cow  in  winter,  then,  when  feeding  40  pounds  of  silage  per 
cow,  a  layer  about  il/2  inches  deep  would  be  fed  off  daily.  When 
silage  is  fed  in  summer  it  is  advisable  that  the  exposed  area  be  not 
over  half  this  size  so  that  a  layer  three  inches  deep  may  be  used 
daily.  However  much  stock  is  to  be  fed,  a  silo  20  to  22  feet  in 
diameter  is  as  large  as  should  be  built.  If  a  silo  is  of  greater 
diameter  than  this,  much  of  the  silage  is  at  too  great  distance  from 
the  door,  increasing  the  labor  of  removal. 

The  deeper  the  silo  the  greater  the  pressure  and  the  more  com- 
pactly will  the  silage  be  pressed  together,  hence  the  larger  the 
amount  that  can  be  stored  per  cubic  foot.  For  example,  a  silo  20 
feet  in  diameter  and  40  feet  deep  will  hold  twice  as  much  as  one 
of  the  same  diameter  and  25  feet  deep.  This  shows  the  economy 
of  reasonably  deep  silos.  To  be  well  proportioned  the  height 
should  not  be  more  than  twice  the  diameter.  No  silo  should  be  less 
than  30  feet  deep  and  to  get  sufficient  depth  for  a  silo  not  over  12 
feet  in  diameter,  it  may  be  placed  4  or  5  feet  into  the  ground. 

The  number  of  tons  of  silage  needed  can  readily  be  estimated 
from  the  size  of  the  herd  and  the  amount  to  be  fed  daily.  Even 
where  it  is  desired  to  feed  as  much  silage  as  possible  not  more  than 
40  pounds  per  cow  should  be  fed  daily.  In  Illinois,  silage  will  usu- 
ally be  needed  from  about  October  20  to  May  10,  or  200  days.  Each 
cow  should  have  an  allowance  then  of  200  times  40  pounds  which 
is  8,000  pounds  of  silage,  or  four  tons  per  cow  for  the  year.  A  herd 
of  ten  cows  will  require  a  silo  holding  40  tons ;  a  herd  of  30  cows 
120  tons ;  50  cows  200  tons ;  and  100  cows  400  tons.  Where  young 
stock  is  raised  an  allowance  should  be  made  for  them.  From  the 
amount  of  silage  needed  the  dimensions  of  a  silo  of  the  required 
capacity  may  be  determined  from  Table  I,  which  gives  the  capacity 
in  tons  of  silos  of  different  diameters  and  depths.  These  estimates 
apply  to  silos  filled  with  well  matured  corn  that  has  been  allowed 
to  settle  forty-eight  hours  and  then  refilled.  It  is  evident  that  to 
get  this  rated  capacity  a  silo  which  had  been  filled  rapidly  must  be 
refilled  after  settling  forty-eight  hours. 


10 


BULLETIN  No.  102. 


I  June  T 


w 
S3 

H 
O 


Q 

H 

G 

a 
a 
n 
§ 
i— i 

J 
J 

H 

O3 

-tl 
X 


o 

3 

CQ 


1905.] 


THE  CONSTRUCTION  OF  SILOS. 


11 


TABLE  1.     APPROXIMATE  CAPACITY  IN  TONS  OP  CYLINDRICAL  SILOS  OF 
DIFFERENT  DIAMETERS  AND  DEPTHS.  COMPUTED  FROM  KING'S  TABLE 

(The  diameter  is  shown  at  the  top  of  the  columns  and  depth  at  the  left) 


INSIDE    DIAMETER    IN    FEET. 


Depth  Ft. 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

20 

26.2 

31.6 

37.7 

44.2 

51.2 

58.8 

67 

75.6 

84.7 

94.4 

104.6 

115.3 

126.6 

21 

28.0 

33.8 

40.3 

47.2 

54.8 

62.9 

71.6 

80.8 

90.6 

100.9 

111.8 

123.3 

135.3 

22 

29.9 

36.2 

43.0 

50.5 

58.6 

67.4 

76.5 

86.4 

96.8 

107.9 

119.6 

131.8 

144.7 

23 

31.9 

38.6 

45.9 

53.9 

62.5 

71.7 

81.6 

92.1 

103.3 

115.1 

127.5 

140.6 

154.3 

24 

33.8 

40.9 

48.7 

57.2 

66.3 

76.1 

86.6 

97.8 

109.6 

122.1 

135.3 

149.2 

163.7 

25 

35.8 

43.3 

51.6 

60.5 

70.2 

80.6 

89.6 

103.6 

116.1 

129.3 

143.3 

158.0 

173.4 

26 

37.9 

45.9 

54.7 

64.2 

74.4 

85.5 

97.2 

109.8 

123.0 

137.1 

151.9 

167.5 

183.8 

27 

40.1 

48.5 

57.7 

67.7 

78.6 

90.2 

102.6 

115.8 

129.8 

144.7 

160.3 

176.7 

194.0 

28 

42.2 

51.1 

60.8 

71.3 

82.7 

95.0 

108.1 

122.0 

136.8 

152.4 

168.9 

186.2 

204.3 

29 

44.4 

53.7 

63.9 

75.0 

87.0 

99.9 

113.7 

128.3 

143.9 

160.3 

177.6 

195.8 

214.9 

30 

46  6 

56  4 

67.2 

78.8 

91.4 

105.0 

119.4 

134.8 

151.1 

168.4 

186.6 

205.7 

99f>   8 

31 

48.8 

59.1 

70.3 

82.5 

95.7 

109.8 

124.9 

141.1 

158.2 

176.2 

195.2 

215.3 

236.3 

32 

51.1 

61.9 

73.6 

86.4 

100.2 

115.1 

130.9 

147.8 

165.7 

184.6 

204.6 

225.5 

247.5 

33 

53.4 

64.6 

77.0 

90.3 

104.8 

120.5 

137.8 

154.6 

173.2 

193.1 

214.1 

235.8 

258.7 

34 

55.8 

67.5 

80.3 

94.3 

109.3 

126.0 

142.8 

161.6 

180.8 

201.7 

223.6 

246.2 

270.0 

35 

58.2 

70.4 

83.7 

98.3 

114.0 

131.6 

148.9 

168.7 

188.3 

210.5 

232.2 

256.8 

281.5 

36 

60.6 

73.0 

86.9 

102.2 

118.3 

136.3 

154.7 

175.9 

196.3 

219.4 

242.0 

267.5 

292.1 

37 

63.1 

76.0 

90.4 

106.1 

123.1 

142.1 

160.8 

183.2 

204.3 

228.0 

251.9 

278.4 

303.9 

38 

65.5 

79.0 

94.0 

110.3 

127.9 

148.0 

167.0 

190.7 

212.4 

237.2 

261.9 

289.4 

315.9 

39 

67.9 

82.0 

97.3 

114.5 

132.8 

154.0 

173.5 

198.3 

220.6 

246.5 

272.0 

300.5 

328.1 

40 

70.3 

85.1 

101.1 

118.8 

137.8 

160.1 

180.0 

205.0 

228.9 

255.9 

280.2 

311.8 

340.4 

ROUND  WOOD  SILO  PLASTERED  WITH  CEMENT 

The  silo  described  below,  which  is  20  feet  in  diameter  and  34^2 
feet  deep,  having  a  capacity  of  228  tons,  was  built  at  the  University 
of  Illinois  the  summer  of  1903.  The  first  silos  of  this  kind  built 
in  the  state,  so  far  as  known  by  the  writer,  were  three  erected  by 
Mr.  H.  B.  Curler  of  DeKalb  in  1897.  (This  is  the  style  of  construc- 
tion frequently  referred  to  as  the  Curler  silo.)  These  three  silos 
have  been  filled  every  year  and  have  given  most  excellent  satisfaction. 
It  seems  probable  that  silos  of  this  construction  will  not  only  preserve 
the  silage  perfectly  but  will  prove  to  be  lasting  as  well  as  economical 
for  most  sections  of  the  state.  As  few  silos  of  this  type  have  as  yet 
been  built  in  Illinois,  a  detailed  description  of  the  one  at  the  Univer- 
sity is  given. 

The  excavation  and  foundation  were  made  by  cutting  a  circle 
20  feet  10  inches  in  diameter  and  four  feet  deep,  and  laying  up  a  four- 
inch  brick  wall  against  the  clay.  (Cut  n.)  This  wall  was  slushed 
in  full  on  the  back  side  with  mortar  so  that  every  brick  had  a  full 


12 


BULLETIN  No.  102. 


[June, 


1905.]  THE  CONSTRUCTION  OF  SILOS.  13 

bearing  against  the  clay  to  resist  the  great  outward  pressure  of  the 
silage.  Where  the  clay  is  solid  a  two-inch  brick  wall  is  quite  suffi- 
cient. Three  feet  from  the  bottom  and  within  one  foot  of  the  top 
of  the  ground  the  wall  was  thickened  to  eight  inches  and  carried  up 
six  inches  above  the  grade  line.  Where  the  grass  is  not  kept  down 
around  the  silo  the  brick  wall  should  be  higher  to  protect  the  wood 
from  dampness. 

When  a  silo  is  placed  in  the  ground,  unless  there  is  good  natural 
drainage  through  the  subsoil,  tile  must  be  laid  to  drain  the  bottom 
or  difficulty  is  almost  sure  to  be  experienced  with  water  in  the  pit. 

The  wall  of  this  silo  should  have  been  strengthened  by  imbed- 
ding an  iron  hoop  in  it  just  above  the  ground,  for  an  eight-inch 
brick  wall  does  not  have  sufficient  strength  to  withstand  the  outward 
pressure  of  the  silage  at  such  a  depth.  This  silo  wall  has  cracked 
slightly  in  two  or  three  places. 

The  sill  was  made  of  2x4/3  cut  into  two  foot  lengths ;  these  were 
thoroughly  imbedded  in  mortar  on  top  of  the  wall.  The  upper  two 
feet  of  the  wall  was  laid  in  mortar  made  of  one  part  Portland  cement 
to  two  parts  of  sharp  sand,  and  the  entire  foundation  was  plastered 
with  a  thin  coat  of  this  mortar. 

The  studs,  which  were  16  foot  2x4/3,  were  set  on  the  sill  and  toe- 
nailed  to  it.  A  large  post  sixteen  feet  long  was  set  in  the  ground  in 
the  center  of  the  excavation,  and  boards  extending  from  this  to  the 
studs  about  six  feet  above  the  foundation,  held  the  studs  perpendicu- 
lar to  this  height.  (Cut  12.)  A  half-inch  board  was  then  bent 
around  the  outside  of  the  studs  at  this  height  and  the  studs  were 
tacked  to  it  as  fast  as  they  were  plumbed.  These  boards  held  the 
studs  perpendicular  and  in  a  circle  to  a  height  of  six  feet.  The  lining, 
which  was  3/2x6  inches  16  feet  long,  made  by  splitting  common 
fencing  with  a  saw,  was  put  on  the  inside,  beginning  at  the  bottom. 
(Cut  13.)  The  upper  portions  of  the  studs  were  then  plumbed  and 
held  in  place  by  pieces  radiating  from  the  post  in  the  center  and  by 
boards  sprung  on  the  circumference  of  the  silo.'  (Cut  13.)  To  in- 
sure uniform  strength  throughout  the  silo,  care  must  be  exercised  to 
break  joints  when  ceiling. 

Staging  was  carried  up  on  the  inside  as  fast  as  the  ceiling.  When 
the  top  of  the  first  studs  was  reached,  the  upper  studs  were  spiked 
to  the  sides  of  the  lower,  allowing  them  to  lap  two  feet,  and  another 
section  was  plumbed.  (Cut  14.)  The  ceiling  was  continued  on  the 
inside  to  within  six  inches  of  the  top,  and  the  plate,  which  consisted 
of  2x4 's  cut  into  two-foot  lengths,  was  then  spiked  on  top  of  the 
studs.  (Cut  15.) 


14 


BULLETIN  No.  102. 


[June, 


BO 


X 

h-l 

Cfl 


o 

o 

J 

55' 


1905.} 


THE  CONSTRUCTION  OF  SILOS. 


15 


16 


BULLETIN  No.  102. 


[June, 


CUT  15. — INSIDE  CEILING  COMPLETED.    CONDITION  IN  WHICH  THE  SILO 
STOOD  FOR  Six  WEEKS  AFTER  FILLING. 


1905.] 


THE  CONSTRUCTION  OP  SILOS. 


17 


DETAIL  °F  OPENING 


CUT  16. — SHOWING  CONSTRUCTION  OF  DOOR  AND  DOOR  FRAME. 

On  each  side  of  the  line  of  doorways  were  set  two  2x4*3  spiked 
together  to  make  4x4's.  These  were  placed  so  that  the  edge  of  the 
2x4*5  faced  the  doorways  leaving  the  flat  side  for  the  doors  to  rest 
against  in  resisting  the  pressure  from  the  silage.  'In  this  way  there 
was  no  crack  through  the  4x4'$  where  the  plaster  and  doors  join. 
(Cut  16.) 

As  the  silo  was  partially  cut  in  two  on  the  side  where  the  open- 
ings were  left,  it  was  necessary  to  reinforce  it  between  the  doors. 
The  strongest,  cheapest,  and  most  satisfactory  way  to  do  this  was  to 
ceil  that  side  of  the  silo  with  an  extra  thickness  from  the  bottom  to 
the  top,  using  half-inch  lumber,  the  same  as  that  with  which  the 
silo  was  lined.  The  doorways  were,  of  course,  left  in  the  middle  of 


18 

11 

i 

i 

I 

Hy 

n 

*  *•  . 

1       f 

E 

1-4 

I  r 
| 

Bu 

n   n   f 
1   ij   i|   ' 

—  h  —  °,  — 

LLI 

^ 

!    i 

1    | 

J  r 

:TIN  No 

n    r 

li  L, 

.  1 

|   n 
i 
•  —  ~ 

02. 

f 

1     f 

i     i 

i  

1 

J 

i 
i 

1  \\ 

[ 

, 

4 

1 

-^ 

^ 

\Ju 

n 

i    i 

;  —  n 

ne, 

n 

\  i 
H 

U_ 
H— 

"T 

'  ! 

r 

4  —  , 

'  11  M  
LJ  L!  

i  —  H  —  p 

r 

.  L 

,  — 

j  —  i. 

H  r 

,  L 

"I 

1 

L4_ 
Hi- 
t-t- 

rr 

u  u  u  u  u 

INTEGIOE  BEFORE   LATttlNG 

CUT  17.— DETAIL  OF  EXTRA  LINING  SHOWING  METHOD  OF  REINFORCING  THE 

SIDE  OF  SILO  IN  WHICH  DOORWAYS  WERE  LEFT.    FIGURES  INDICATE 

ENDS  OF  BOARDS  SHOWING  METHODS  OF  BREAKING 

JOINTS  ON  INNER  LINING. 

this  extra  ceiling  and  the  spaces  between  the  doors  were  thus  cov- 
ered with  two  thicknesses,  with  no  broken  joints  for  14  feet,  as 
shown  in  Cut  17.  The  ends  of  the  boards  of  this  inner  lining  broke 
joints  on  three  studs  so  that  all  of  the  strain  at  the  end  of  these 
boards  should  not  come  at  one  stud.  These  irregular  ends  were 
filled  out  with  short  pieces  so  that  the  edge  of  the  extra  thickness 
would  come  in  a  straight  line.  Since  this  inner  ceiling  left  a  jog  of 
a  half  inch,  the  thick  edge  of  common  shingles  was  butted  against 
the  ends  of  the  half-inch  boards,  thus  running  the  extra  thickness 
down  to  a  feather-edge  and  making  an  apparently  even  surface  on 
which  to  lath.  (Cut  17.) 

The  silo  was  then  lathed  with  common  four-foot  lath,  breaking 
joints  as  shown  in  Cut  18,  and  nailing  the  lath  solid  to  the  half-inch 
ceiling  without  furring  out.  It  is  usually  recommended  in  lathing 
silos  that  the  edges  of  the  lath  be  cut  on  a  bevel  so  that  when  nailed 
to  the  wall  a  dove-tailed  joint  is  formed  for  the  mortar,  or  that  the 
lath  be  set  out  on  furring  strips  so  that  the  mortar  may  clinch  be- 
hind the  lath.  Experience  shows  that  this  is  entirely  unnecessary. 

The  plaster  was  made  of  one  part  Portland  cement  to  two  parts 
of  good  sharp  sand.  Two  coats  of  this  mortar  were  used  making 
the  plaster  a  full  half-inch  thick  over  the  lath.  The  second  coat 
extended  continuously  from  the  bottom  of  the  brick  work  to  the  top 
of  the  silo,  uniting  the  foundation  and  the  superstructure  and 
giving  an  air-tight  wall  for  the  entire  silo. 

Four  doors  were  made  of  two  thicknesses  of  common  flooring 
run  in  opposite  directions  with  tar  paper  between.  These  doors  are 
each  20  inches  wide,  2^  feet  high,  and  are  four  feet  apart.  The  top 
of  the  upper  door  is  five  feet  below  the  plate,  but  by  the  time  the  silo 


1905.] 


THE  CONSTRUCTION  OP  SILOS. 


19 


o 

K 
CO 

o 
hJ 

CO 


20 


BULLETIN  No.  102. 


[June, 


PLATE 


is  opened  the  silage  has  usually  settled  nearly  to 
the  top  of  the  upper  door  so  that  but  little  silage 
has  to  be  removed  before  the  door  can  be  taken 
out.  The  size  and  location  of  the  four  doors 
are  shown  in  Cut  19  and  a  section  of  one  of 
them  in  Cut  16. 

Authorities  on  silo  construction  have  errone- 
ously stated  that  for  silos  20  feet  in  diameter 
and  30  feet  deep,  three  thicknesses  of  half-inch 
lumber  are  required  to  give  sufficient  strength. 
This  silo  is  30  feet  in  height  above  the  founda- 
tion and  as  the  pressure  of  silage  at  this  depth 
is  330  pounds  per  square  foot  there  is  a  tensile 
pull  on  the  sides  of  the  bottom  foot  of  a  silo  of 
these  dimensions  of  3300  pounds.  In  this 
lower  foot  to  resist  this  strain,  there  are,  of 
course,  two  boards  each  one-half  inch  thick  and 
six  inches  wide,  making  a  total  area  of  six 
square  inches  of  lumber.  On  account  of  the 
great  tensile  strength  of  wood  it  was  thought 
that  this  one  layer  of  half-inch  lumber  would  be 
sufficient  to  withstand  the  strain.  To  deter- 
mine if  this  were  true,  the  silo  as  shown  in  Cut 
15  was  filled  and  after  standing  six  weeks  did 
not  show  the  slightest  sign  of  giving  in  any 
particular. 

In  order  to  preserve  the  silo  in  good  condi- 
tion it  is  absolutely  necessary  that  the  half -inch 
lumber  with  which  the  silo  is  ceiled,  be  pro- 
tected from  dampness.  To  this  end  the  plaster 
must  be  of  good  quality  and  kept  perfectly 
water-tight  by  cementing  up  any  cracks  that 
may  appear,  so  that  the  wood  shall  receive  no 
moisture  from  the  silage.  The  wall  must  also 
be  ventilated,  for  by  allowing  a  free  circulation 
of  air  between  the  sheeting  and  the  lining,  the 
lumber  will  be  kept  dry.  In  this  silo  a  two-inch 
space  was  left  at  the  top  above  the  plaster  and 
below  the  plate.  In  this  way  the  air  was  al- 
lowed free  access  to  enter  from  the  bottom,  be- 
tween the  outside  covering  and  the  inside  lining,  and  pass  into  the 
silo  through  the  openings  at  the  top.  These  spaces  were  covered 
with  heavy  wire  netting  of  one-third  inch  mesh  to  keep  out  rats  and 
mice.  (Cut  20.) 


T3 

5 

b" 

^ 

a 

6' 

4 

0" 

DOOR. 

*' 

6" 

4 

X 

DQW2 

z' 

6" 

< 

X 

i 

G" 

« 

fa" 

M  EIGHT   Or  OPE.MIMG5 

CUT  19,     -- 


1905.] 


THE  CONSTRUCTION  OF  SILOS. 


21 


QE.TAIL 


WAT£.R  TABLE 


f)ETAILOF  J3A3C 


CUT  20.— DETAIL  AT  TOP  AND  BOTTOM  OF  SILO  SHOWING  SYSTEM  OF 

VENTILATING  THE  WALL.    OPENINGS  COVERED  WITH  WIRE 

NETTING  TO  KEEP  OUT  RATS  AND  MICE. 


22  BULLETIN  No.  102.  [June, 

Theoretically  the  outside  covering  should  be  put  on  horizontally 
so  that  the  strength  of  the  material  which  forms  the  cover  might  add 
to  the  strength  of  the  silo.  There  are,  however,  several  practical 
difficulties  in  putting  sheeting  on  in  this  manner.  The  lumber 
cannot  be  more  than  a  half-inch  thick  and  spring  to  a  circle  twenty 
feet  or  less  in  diameter,  and  any  siding  as  thin  as  this,  which  is 
carried  in  stock,  is  practically  clear  lumber  and  necessarily  high 
priced.  Another  difficulty  is  that  the  only  half-inch  stuff  that  can 
be  purchased  at  the  lumber  yard,  which  will  make  a  water-tight 
cover,  is  common  house  siding.  This,  in  order  to  be  sprung  to  a 
circle,  must  be  rabbeted  on  the  back  side  of  the  thick  edge  so  as  to 
fit  over  the  thin  edge  of  the  board  below  and  allow  the  siding  to  lie 
flat  against  the  studs.  Rabbeted  siding  cannot  usually  be  obtained 
at  a  lumber  yard  and  it  is  extra  trouble  and  expense  to  have  this 
work  done  at  a  mill.  Another  serious  difficulty  in  putting  the  siding 
on  horizontally  is  that  at  the  end  of  each  board  there  is  a  strong 
outward  pull  against  the  nail  heads  and  as  soon  as  the  boards  be- 
come slightly  decayed  at  the  ends  they  are  likely  to  pull  off  over  the 
nails. 

Owing  to  these  objections  and  to  the  fact  that  it  was  our  aim  to 
use,  as  nearly  as  possible,  lumber  that  is  carried  in  stock  by  all 
lumber  yards,  it  was  decided  to  put  hoops  on  the  outside  and  build 
them  up  of  the  same  half-inch  material  as  the  inside  sheeting.  This 
was  done  by  using  three  thicknesses  and  breaking  joints,  thus  mak- 
ing a  strong  six-inch  hoop  il/2  inches  thick.  Seven  of  these  were 
placed  around  the  silo  between  the  doors  to  make  a  continuous  even 
surface  on  which  to  nail  the  sheeting.  The  silo  was  sheeted  up  and 
down  with  common  1x12  barn  boards  14  and  16  feet  long,  and  the 
cracks  were  covered  with  common  three-inch  battens. 

Some  silos  are  sheeted  on  the  outside  with  the  same  half-inch 
lumber  as  is  used  on  the  inside,  having  the  edges  cut  to  a  bevel  so 
that  the  cracks  slant  outward  and  downward.  The  same  difficulties 
are  encountered  here,  however,  as  were  mentioned  above  and  such 
siding  is  not  perfectly  water-tight  as  the  rain  may  drive  in  between 
the  cracks.  When  the  siding  is  put  on  horizontally  it  should  be  car- 
ried up  as  fast  as  the  ceiling  inside,  thus  obviating  the  necessity  of 
building  staging  on  the  outside. 

After  the  silo  wall  was  completed  a  conical  shingled  roof  was  put 
on,  a  chute  built  over  the  doors  through  which  the  silage  is  thrown 
down,  and  the  small  space  between  the  silo  and  the  barn  roofed  over, 
connecting  the  two.  The  silo  was  then  completed  ready  for  paint- 
ing. (Cut  21.) 


1905,  \ 


THE  CONSTRUCTION  OF  SILOS. 


23 


CUT  21.— THE  SILO  COMPLETE,  SHOWING  CHUTE  THROUGH  WHICH  THE  SILAGE 

is  THROWN  DOWN,  AND  CONNECTION  WITH  THE  BARN.    THE  SMALL 

DOOR  IN  THE  ROOF  is  TO  ADMIT  BLOWER  PIPE  WHILE  FILLING. 


24  BULLETIN  No.  102.  [June, 

The  silo  has  been  filled  twice  and  both  years  the  silage  has 
kept  perfectly  from  the  bottom  to  the  top,  even  next  the  wall  and 
against  the  doors.  As  before  mentioned  the  top  of  the  brick  wall 
cracked,  as  it  was  not  reinforced,  and  the  silage  spoiled  slightly  at 
this  place,  but  this  can  easily  be  remedied  another  year. 

In  the  spring  of  1904  when  the  cows  were  turned  out  to  pasture, 
about  seven  feet  of  silage  remained  in  the  silo.  The  small  silo  for 
summer  feeding  was  then  opened  and  the  rotten  silage  from  the  top 
of  the  small  silo  was  distributed  over  the  good  silage  in  the  large 
silo  to  the  depth  of  about  six  inches.  This  was  thoroughly  soaked 
and  tramped  firmly.  When  ready  to  fill  again  in  the  fall  there  were 
about  eight  inches  of  rotten  silage  to  remove,  only  two  inches  of  the 
good  silage  having  spoiled.  Fresh  corn  was  run  on  the  top  of  this 
and  the  whole  kept  perfectly.  When  feeding  out,  scarcely  any  trace 
of  spoiled  silage  was  to  be  found  at  the  union  of  the  silage  of  the 
different  years. 

The  cost  of  this  silo,  which  was  20  feet  in  diameter  and  34^ 
feet  deep,  holding  228  tons,  was  $383.00  or  $1.68  per  ton 
capacity. 

ITEMIZED  COST  OF  SILO 
Foundation — 

Excavating  4  feet  deep  and  laying  wall 

35  hours  at  30  cents $10.50 

70  hours  at  15  cents 10.50 

2,000  brick  at  $7.25 14.50 

2  barrels  cement  at  $2.00 4.00 

2  barrels  lime 1.55  $41.05 


Superstructure — 

139 — 2x4 — 16  feet,  1,482  feet  at  $20.00. .....  .$29.64 

252 — 5/2x6 — 16  feet,  2,016  feet  at  $14.00. .....   28.22 

4  doors  20x30  inches  double,  33^  at  $23.00 77 

3,100  lath  at  $4.50  per  M T3-95 

1 1  barrels  cement  at  $2.00 22.00 

6  yards  sand  at  $1.25 7.50 

Carpenters,  67  hours  at  30  cents 20.10 

Labor,  148  hours  at  1 5  cents 22.20 

Plastering,  28  hours  at  40  cents 11.20 

Tender,  35  hours  at  15  cents 5.25   160.83 


1905.]                             THE  CONSTRUCTION  OP  SILOS.  25 

Sheeting — 

7  hoops — 84 — y2x6 — 16  ft.    672  ft.  @  $14.00.  9.41 

6 1 — 1x12 — 1 6  ft.     976  ft.  at  $24.00 23.42 

61 — 1x12 — 14  ft.     854  ft.  @   $24.00 20.50 

6 1  battens  ^4x3 — 16  ft.     244  ft.  @   $22.00.  .  5.37 

6 1  battens  ^x3 — 14  ft.    214  ft.  @  $22.00 4.70 

65  ft.  2y2  in.  water  table  @  $3.00  per  C 1.95     65.35 


Roof— 

18 — 2x4 — 14  ft.     168  ft.  @  $19.00 3.19 

3 — 2x4 — 12  ft.     24  ft.  @  $19.00 46 

4,000  shingles  @  $3.20  per  M 12.80 

35  roof  boards  1x6 — 16  ft.     280  ft.  @  $16.00.  .  4.48 

Cornice,  5 — 1x12 — 16  ft.     80  ft.  @  $24.00...  1.92 

Ornamental  post  in  center .90     23.75 


Chute— 

5 — 2x4 — 14  ft.     47  ft.  @   $19.00 89 

12 — 1x12 — 16  ft.     192  ft.  @  $24.00 4.61       5.50 


Carpenter  work  on  roof,  sheeting  of  silo  and  chute — 

54     hrs.  @  3oc 16.20 

120  hours  @  25c 30.00     46.20 


:  Hardware — 

Nails 

50  Ib.     8d  common  @  3c 1.50 

2  Ib.  lod  common  @  5c 10 

8  Ib.     3d  cut  @  4c 32 

6  Ib.  6d  cut  @  4c 24 

4  Ib.  shingle  @  4C 16 

2  Ib.  long  finishing  @  5c 10 

Wire  netting — 

63  sq.  ft.  y3  in.  mesh  @  5^  c 3.47       5.89 


Painting — 

Priming  coat, 

9  gal.  oil  @  5oc 4-5° 

29  Ib.  yellow  ocher  @  SG 1.45 

25  hours  labor  @  I5c 3.75 

Paint  and  labor,  two  coats 25.00     34.70 


Total  cost 383-27 


BULLETIN  No.  102. 


CUT  22.— SILO  CEILED  ON  THE  INSIDE  WITH  Two  THICKNESSES  OF  HALF-INCH 
LUMBER  WITH  PAPER  BETWEEN.    BARN  WAS  BUILT  OVER  SILO  LATER. 


1905.] 


THE  CONSTRUCTION  OF  SILOS. 


27 


O 

O 

» 

DJ 

a 

o 

o 


P 

O 


O 

O 


CO 


28 


BULLETIN  No.  102. 


[June, 


Many  silos  are  built  similar  to  the  one  just  described  excepting 
that  in  place  of  the  lath  and  cement  plaster  the  silo  is  ceiled  with 
another  thickness  of  half-inch  lumber,  using  water-proof  paper  be- 
tween. That  the  lining  shall  be  tight,  the  boards  must  be  of  the  same 
width  and  it  is  necessary  to  have  the  lumber,  dressed  so  that  the 
boards  will  be  of  the  same  thickness  and  will  lie  closely  together. 
This  makes  a  fairly  good  silo  for  a  few  years,  if  built  of  durable 
wood,  but  it  vis  practically  as  expensive  and  does  not  preserve  the 
silage  so  thoroughly. 

The  exterior  covering  of  this  style  of  silo  may  be  the  same  as 
for  a  plastered  silo.  If  built  inside  the  barn  no  roof  or  outer  sheet- 


CUT  24. — Two  SILOS  OF  SAME  CONSTRUCTION  AS  SHOWN  IN  CUT  22,  SHEETED 
WITH  HALF-INCH  LUMBER;  ONE  ON  LEFT  ALSO  COVERED  WITH  TAR  PAPER. 


1905.] 


THE  CONSTRUCTION  OP  SILOS. 


29 


CUT  25.— SAME  CONSTRUCTION  AS  SHOWN  IN  CUT  22;  SHEETED  WITH  HALF-INCH 

LUMBER  TO  A  HEIGHT  OF  Six  FEET  AND  COVERED  WITH  GALVANIZED  IRON. 

AN  EXPENSIVE  COVERING  BUT  DURABLE  AND  SAVES  PAINTING 


30 


BULLETIN  No.  102. 


\June, 


1905.] 


THE  CONSTRUCTION  OF  SILOS. 


31 


CUT  27.— SILO  IN  CENTER  OF  BARN  SHOWN  IN  CUT  26.    UPPER  PORTION    IN 
HAY  LOFT,  LOWER  PORTION  IN  Cow  STABLE. 


32  BULLETIN  No.  102.  [June, 

ing  is  necessary.  In  Cut  22  is  shown  a  silo  of  this  construction 
where  the  barn  is  built  over  it.  Cut  23  shows  a  silo  of  this  style 
ceiled  with  beveled  half-inch  lumber.  In  Cut  24  are  shown  two 
silos  of  the  same  construction  sheeted  with  half-inch  lumber ;  one  be- 
ing covered  with  tarred  felt. 

The  silo  shown  in  Cut  25  is  sheeted  with  half-inch  lumber  to 
a  height  of  six  feet  and  the  entire  surface  is  covered  with  galvanized 
iron.  This  makes  a  good  covering  but  it  is  rather  expensive  as  the 
iron  costs  about  5  cents  a  square  foot. 

From  what  we  now  know,  the  round  wood  silo  plastered  with 
cement  seems  to  be  the  best  construction,  but  the  indications  are  that 
when  we  learn  to  handle  concrete  to  the  best  advantage  this  will  be 
the  material  for  building  silos. 

CONCRETE  SILOS 

Silos  built  of  concrete  have  been  30  feet  deep  with  the  wall  not 
more  than  six  inches  thick  at  the  base  and  tapering  to  four  inches 
at  the  top.  Where  gravel  or  crushed  stone  can  be  obtained  at  a 
reasonable  price  it  may  be  advisable  to  make  the  walls  slightly 
thicker,  and  in  cold  climates  they  should  be  built  with  a  dead-air 
space  in  the  wall  to  prevent  the  silage  from  freezing.  In  any  event 
there  should  be  enough  heavy  wire  or  iron  rods  imbedded  in  the 
wall  to  withstand  the  strain  of  the  silage;  unless  this  is  done  cracks 
are  likely  to  appear.  The  amount  of  wire  necessary  in  each  case 
will  depend  upon  the  size  and  depth  of  the  silo.  The  wall  should  be 
plastered  on  the  inside  with  one  part  of  Portland  cement  to  two  of 
good  sharp  sand  troweled  to  a  smooth  surface.  This  will  resist  the 
action  of  the  acid  in  the  silage. 

Cut  28  shows  an  all-concrete  silo  20  feet  in  diameter  and  42  feet 
deep.  The  wall  is  22  inches  thick  for  the  first  14  feet,  19  inches 
thick  the  next  14  feet,  and  16  inches  thick  the  upper  14  feet.  This 
silo  cost  approximately  $1200,  and  as  it  holds  334  tons,  the  cost 
per  ton  was  $3.59.  While  the  first  cost  of  this  silo  was  high  it  may 
prove  economical  in  the  end  as  it  should  stand  for  more  than  a 
hundred  years. 

It  is  essential  that  a  concrete,  stone,  or  brick  silo  have  a  good 
foundation,  otherwise  it  is  likely  to  settle  unevenly  and  cracks  will 
appear  in  the  wall,  giving  the  air  a  chance  to  enter.  If  the  silo  is 
put  at  least  three  feet  into  the  ground  this  assures  a  firm  footing 
and  also  adds  to  the  depth  of  the  structure. 


1905  .] 


THE  CONSTRUCTION  OF  SILOS. 


33 


CUT  28.— CONCRETE  SILO  20  FEET  IN  DIAMETER  AND  42  FEET  DEEP; 
CAPACITY  334  TONS. 


34 


BULLETIN  No.  102. 


[June, 


There  are  great  possibilities  in  reinforced  concrete  and  a  cir- 
cular structure  is  the  best  to  be  easily  reinforced.  Silos  have  been 
built  of  concrete  but  usually  with  solid  walls  and  much  thicker  than 
necessary.  The  method  of  construction  heretofore  has  in  most  cases 
been  cumbersome,  requiring  a  large  amount  of  lumber  to  construct 
the  forms.  With  unskilled  labor  the  question  of  concrete  silos  is 
still  a  problem.  Good  grades  of  cement  are  now  manufactured  in 
the  state  and  are  becoming  much  cheaper.  Machines  have  already 
been  made  with  which  reinforced  continuous  hollow  walls  are  built 
with  comparative  ease,  and  when  we  learn  how  to  handle  cement  to 
the  best  advantage  possible  this  will,  undoubtedly,  be  the  silo  of  the 
future,  especially  in  sections  where  sand  and  gravel  or  crushed  stone 
are  abundant. 


CUT  29. — BRICK  SILO  WITH  DEAD-AIR  SPACE  IN  WALL. 


1905.  J 


THE  CONSTRUCTION  OF  SILOS. 


35 


We  expect  to  investigate  the  subject  of  concrete  silos  during  the 
coming  year  and  erect  one  or  two  small  ones  of  this  construction  at 
the  University. 

BRICK  SiivOS 

Where  brick  is  cheap  and  stone  and  gravel  scarce,  a  brick  silo 
may  be  the  most  economical.  In  large  brick  silos  the  wall  is  usually 
built  with  three  or  four  courses  of  brick  at  the  base  and  made  a 
course  thinner  at  various  heights  until  reaching  the  upper  ten  feet, 
which  need  not  be  more  than  eight  inches  thick.  Cut  29  shows  a 
brick  silo  built  on  this  plan.  This  silo  rests  upon  a  seven-foot  stone 


CUT  30.— STONE  SILO  18  FEET  10  INCHES  IN  DIAMETER  AND  30  FEET  DEEP; 
CAPACITY  156  TONS.    COST  ABOUT  $600 


36 


BULLETIN  No.  102. 


[June, 


foundation  18  inches  thick;  six  feet  of  it  being  below  the  ground. 
Upon  this  are  laid  three  courses  of  brick,  the  middle  course  being 
of  brick  tile  which  contains  a  dead-air  space  and  thus  prevents  freez- 
ing to  a  great  extent.  This  wall  extends  twelve  feet  above  the 
foundation  and  from  that  point  to  the  top,  two  courses  of  brick  are 
used  with  one  and  a  half  inch  air  space  between.  One  silo  16  feet  in 
diameter  and  30  feet  deep,  built  in  this  manner,  holds  120  tons  and 
cost  $250,  or  $2.08  per  ton.  Another  silo  of  the  same  depth  and 
19  feet  in  diameter  holds  168  tons  and  cost  $350,  or  $2.08  per  ton,, 
the  same  as  the  smaller  silo. 

STONE  SILOS 

Where  stone  can  be  easily  and  cheaply  obtained  silos  may  be 
built  of  this  material.  Cut  30  shows  a  stone  silo  which  is  18  feet  10 
inches  in  diameter  and  30  feet  deep,  holding  156  tons.  The  wall  of 
this  silo  is  two  feet  thick  and  extends  five  feet  into  the  ground. 
The  portion  below  the  surface  is  made  of  hardheads  while  that  above 
is  of  quarry  stone  obtained  from  a  neighboring  farm.  The  inside 
is  plastered  with  Portland  cement.  The  first  door  is  2x6  feet,  the 
next  2x3  and  the  upper  2x4  feet.  This  silo  cost  $500  besides  the 


CUT  31. — STONE  SILO  20  FEET  IN  DIAMETER  AND  32  FEET  DEEP: 
CAPACITY  204  TONS.    COST  NEARLY  $700. 


1905.}  THE  CONSTRUCTION  OF  SILOS.  37 

labor  of  the  owner  which  amounted  to  about  $100,  making  the  total 
cost  $600,  or  $3.64  per  ton  capacity.  Although  the  material  may  be 
cheap  and  close  at  hand  the  expense  of  elevating  heavy  stone  for 
so  thick  a  wall  and  the  employment  of  a  stone  mason,  which  is  high 
priced  labor,  make  a  stone  silo  expensive. 

The  silo  shown  in  Cut  31,  is  20  feet  in  diameter  and  32  feet 
deep,  having  a  capacity  of  204  tons.  This  silo  extends  eight  feet  into 
the  ground,  which  is  too  deep,  requiring  extra  labor  in  removing 
the  silage.  The  wall  of  the  lower  12  feet  is  24  inches  thick  and 
above  this  it  is  18  inches.  The  wall  is  plastered  with  a  half-inch 
coat  of  cement  and  the  bottom  is  covered  with  three  inches  of  con- 
crete. Iron  rods  were  laid  in  the  wall  just  above  and  below  the 
doors.  The  stone  cost  $3.50  per  cord  and  was  hauled  seven  miles. 
Sixty-three  loads  of  sand  were  bought  at  ten  cents  a  load  and 
hauled  four  miles.  The  total  cost  for  material,  masons,  and  car- 
penter, was  $535,  but  this  does  not  include  excavating,  the  haul- 
ing of  material,  tending  masons,  and  boarding  men.  If  all  these 
expenses  were  included  it  would  probably  make  the  total  cost  about 
$700. 

Stone  silos  preserve  the  silage  perfectly  and  are  permanent,  re- 
quiring little  outlay  for  maintenance;  the  only  objection  being  the 
excessive  first  cost. 

STAVE  SILOS 

There  are  cases  where  a  cheap,  temporary  silo  may  be  economical 
and  of  great  advantage,  for  example,  a  farmer  may  expect  to  build  a 
new  barn  in  a  different  place  and  want  a  silo  near  the  old  barn 
for  a  few  years  only;  or  a  renter  may  wish  a  temporary  silo  and 
then  if  he  moves  in  a  short  time  he  can  take  the  lumber  from  a  stave 
silo  with  him. 

The  objections  to  a  stave  silo  are  that  the  staves  shrink  during 
dry  weather  when  the  silo  is  empty  and  unless  the  hoops  are  tightened 
there  is  a  possibility  of  the  silo  being  racked  or  blown  over.  If  the 
hoops  are  tightened  when  the  staves  are  dry,  there  is  then  danger 
of  the  hoops  bursting  when  the  silo  is  filled  and  the  staves  again  be- 
come saturated  with  moisture.  An  example  of  this  came  under  the 
writer's  notice  recently  when  the  second  morning  after  a  silo  was 
filled,  the  owner  found  half  the  hoops  had  burst.  It  will  be  noticed 
in  the  illustrations  of  stave  silos  that  where  they  had  been  put  up 
for  any  length  of  time  the  staves  had  shrunk  allowing  the  hoops  to 
drop  from  their  original  position.  A  stave  silo  is  usually  much 


38 


BULLETIN  No.  102. 


[June, 


CUT  32. — STAVE  SILO  WITHOUT  ROOF,  16  FEET  IN  DIAMETER  AND  34  FEET 

DEEP;  CAPACITY  150  TONS.    To  BE  RECOMMENDED  ONLY 

WHERE  A  TEMPORARY  SILO  is  DESIRED. 


1905.] 


THE  CONSTRUCTION  OF  SILOS. 


.     39 


CUT  33.  -STAVE  SILO  20  FEET  IN  DIAMETER  AND  34  FEET  DEEP;  CAPACITY  224 

TONS.    THE  STAVES  HAVE  SHRUNK  WHEN  EMPTY  ALLOWING 

HOOPS  TO  DROP  FROM  ORIGINAL  POSITION. 


40 


BULLETIN  No.  102. 


[June, 


1905.]  THE  CONSTRUCTION  OF  SILOS.  41 

more  satisfactory  if  a  building  is  built  over  it  for  protection,  but 
this  makes  it  expensive. 

Cut  32  shows  a  stave  silo  recently  built.  This  silo  is  16  feet  in 
diameter,  34  feet  deep,  and  has  a  capacity  of  150  tons.  The  founda- 
tion, which  extends  two  feet  into  the  ground,  is  a  brick  wall  that 
was  laid  up  by  the  owner.  The  silo  was  built  by  two  carpenters  in 
nine  days  at  $2.50  a  day  each,  making  $45  paid  out  for  labor.  The 
lumber  cost  $80,  the  iron  hoops  $20,  and  nails  and  spikes  $2.  There 
being  no  roof  the  silo  above  the  foundation  cost,  including  labor, 
$147.  If  the  brick  had  been  purchased  and  the  labor  of  excavating 
for  the  foundation  and  laying  the  brick  charged  for,  the  total  cost  of 
the  silo  would  have  been  approximately  $170  without  a  roof,  or 
$1.13  per  ton. 

The  staves  were  rough  white  pine,  2x4,  14  and  18  feet  long  to  make 
the  required  height.  Four  4x6  uprights  were  placed  on  the  founda- 
tion in  the  circle  90  degrees  apart,  holes  having  been  bored  in  them  to 
receive  the  iron  hoops  which  had  threads  cut  on  the  ends.  The  staves 
were  then  set  in  the  circle  alternating  in  length  so  as  to  break  joints. 
As  each  2x4  was  set  up  it  was  fastened  to  the  next  one  by  means 
of  six  inch  spikes  which  were  driven  through  the  2x4's  edgewise, 
^piking  -in  this  way  makes  the  silo  much  more  rigid  and  it  is  not  so 
likely  to  be  racked  or  blown  down  when  empty.  When  all  the  staves 
were  in  place  the  silo  was  tightened  by  turning  up  the  nuts  at  the 
ends  of  the  iron  hoops  on  either  side  of  the  4x6's.  The  hoops  are 
much  closer  together  at  the  bottom  than  at  the  top  to  give  the  added 
strength  necessary  where  the  pressure  is  the  greatest. 

Four  doors  18  inches  wide  and  two  feet  high  were  cut  in  the 
side,  one  above  the  other,  about  six  feet  apart.  Outside  of  these 
was  built  a  chute  to  prevent  the  silage  from  being  blown  away  when 
thrown  down. 

There  are  several  firms  who  manufacture  stave  silos  and  send 
them  out  in  any  size  desired,  ready  .to  set  up.  Many  of  these  are 
made  of  durable  wood  and  give  good  satisfaction.  One  of  these 
silos  is  illustrated  in  Cut  33. 

While  it  is  true  that  a  stave  silo  may  be  used  to  advantage  in 
some  cases,  yet  where  a  permanent  silo  is  desired  either  the  wood 
silo* plastered  with  cement,  or  the  grout,  or  brick  structure  will  un- 
doubtedly prove  most  satisfactory,  both  on  account  of  greater  per- 
manency and  the  better  preservation  of  the  silage. 


—   rxHL 

>4mff2r> 


